No parts of the original Otto need to be modified for it to work. It's plug-and-play! The attached .ino file is the programming for the Nano. It's the same code as the one in Otto the Tissue Butler!

It uses the ultrasonic sensor to detect a gesture 10 cm away to trigger the actions. Afterwards, taking a few steps towards you and patiently waiting for you to get the amount of tissue you need. It will celebrate with a happy gesture and walk backwards.

Print settings :

1. Wall count — 3 or more;
2. Top and bottom layers — 3;
3. Infill — 20%, grid;
4. Layer height — 0.2 mm.

All parts are printed with a 0.4 mm nozzle.

Assembly :

Be careful when handling the penknife when cutting the styrofoam to fit inside the heart case and slits to hold the rings in!

The bow tie goes in just like how the matrix LED housing is supposed to. The arms use M6 bolts and nuts to fix them in place. 

Please refer to the images below.

Nut traps are a staple of 3D printing and here are somemore showcasing them! M3 bolts and nuts are used for the ring holder attachments. 4 M3 x 12 bolts for the inclined heart are used whereas 2 M3 x 16 bolts are for the hand pegs. The following are some pictures of them.

To see Otto the Ring Butler or his other cousin (i.e., the Tissue Butler) do their thing, you may visit my Instagram, @printed.hands! 

Have fun!